Want to see how others played a song? Check the song leaderboard. You can access it by selecting the score located in the top right hand corner of the song screen.
Once you have played the song, you can see your score on the leaderboards. You can also toggle between My level, Global and Friends views.
If you play a past Weekly challenge song, your score is saved but the Weekly challenge leaderboard is not updated. You can view your score for the song from the song summary screen. You can also find the song with song search. Open the song and select the score in the top right hand corner to view your standing on the song leaderboard.